This invention relates generally to improvements in infusion pumps of the type used for controlled delivery of medication to a patient. More specifically, this invention relates to an improved medication infusion pump having a modified and space-efficient flexible drive member.
Infusion pump devices and systems are relatively well-known in the medical arts, for use in delivering or dispensing a prescribed medication such as insulin to a patient. In one form, such devices comprise a relatively compact pump housing adapted to receive a syringe carrying a prescribed medication for administration to the patient through infusion tubing and an associated catheter or the like. The infusion pump includes a small drive motor connected via a lead screw assembly or the like for motor-driven advancement of a syringe piston plunger to administer the medication to the patient. Programmable control means are normally provided for operating the drive motor continuously or at periodic intervals to obtain a closely controlled and accurate delivery of the medication over an extended period of time. Such infusion pumps are utilized to administer insulin and other medications, with exemplary pump constructions being shown and described in U.S. Pat. Nos. 4,562,751; 4,678,408; 4,685,903; 4,562,751; 4,678,408; 4,685,903; 5,080,653; and 5,097,122, which are incorporated by reference herein. Moreover, such infusion pumps are available from MiniMed Technologies of Sylmar, Calif. under Model Nos. 504 and 506.
Infusion pumps of the general type described above have provided significant advantages and benefits with respect to accurate delivery of medication over an extended period of time. The infusion pump is often designed to be extremely compact and may thus be adapted to be carried by the patient, for example, by means of a belt clip or the like. As a result, important medication can be delivered to the patient with precision and in an automated manner, without significant restriction on the patient's mobility or life-style.
In the past, the physical size of the medication in fusion pump and/or the medication-carrying capacity of the pump has been a function of the length of the medication-containing syringe with the piston plunger thereof in a fully retracted state. The pump drive motor engages and advances the piston plunger slowly on a continuous or incremental basis, such that the effective length of the syringe and plunger gradually decreases as the medication is delivered to the patient. To achieve a desirably compact pump design which is both convenient and inobtrusive to the patient, the medication-carrying capacity of the syringe has been limited to relatively small volumes. It has not been possible to increase the available volume of medication in a compact pump profile without undesirably increasing the physical size of the infusion pump.
There exists, therefore, a significant need for improvements to medication infusion pumps, particularly with respect to reducing the size of the pump device without reducing the medication-carrying capacity. In the alternative, there exists a significant need for an improved medication infusion pump with an increased medication-carrying capacity without a corresponding increase in the size of the pump device. The present invention fulfills these needs and provides further related advantages.